Add the possibility to add/remove sensors from Berdy

[lrapetti]

Currently in BERDY is using internally sensors defined as BerdySensorTypes. Those sensor types can be be:

• copy of iDynTree::sensorsType

  SIX_AXIS_FORCE_TORQUE_SENSOR = SIX_AXIS_FORCE_TORQUE,
  ACCELEROMETER_SENSOR = ACCELEROMETER,
  GYROSCOPE_SENSOR = GYROSCOPE,
  THREE_AXIS_ANGULAR_ACCELEROMETER_SENSOR = 
  THREE_AXIS_ANGULAR_ACCELEROMETER,
  THREE_AXIS_FORCE_TORQUE_CONTACT_SENSOR  = 
  THREE_AXIS_FORCE_TORQUE_CONTACT,
  

• custom sensor used in berdy ("berdy specific sensors")

  DOF_ACCELERATION_SENSOR = 1000,
  DOF_TORQUE_SENSOR       = 1001,
  NET_EXT_WRENCH_SENSOR   = 1002,
  JOINT_WRENCH_SENSOR     = 1003

Those sensor are add to the BerdyHelper in the init() function and are add accordingly to the type in two way:

• trough a SensorsList that is a list of iDynTree::sensorType(that for example can be extracted from an URDF). For the sensor list we are able to add/remove object from the list before passing it to the init()
• The berdy specific sensor are add accordingly to some berdy option passed to the init(). Those options allows only to select all/select none of the berdy specific sensors:

  includeAllJointAccelerationsAsSensors(),
  includeAllJointTorquesAsSensors(),
  includeAllNetExternalWrenchesAsSensors(),
  

  (only the joint wrench are selected in a different way by filling a vector containing the joint for which the sensor exist, see: https://github.com/robotology/idyntree/blob/devel/src/estimation/include/iDynTree/Estimation/BerdyHelper.h#L222)

What is missing is the possibility of adding/removing a single sensor from the berdy specific sensors. There are multiple way to do that, those are some options:

• One solution may be to use a sensor list inside the berdyOption similarly to what done for the JOINT_WRENCH_SENSOR so that the sensor can be add one by one in the BerdyOption, or add all and then eventually removed.
• build a vector of berdy sensor that may be build trough options and iDynTree sensors, and that can be access to add/remove sensor. And then pass this vector to the BerdyHelper::init()
• Use all the sensor as iDynTree sensors (adding the missing sensors)

[traversaro]

Any one of the proposed solution seems fine to me. Feel free to propose a PR, thanks!